Medical balloon

ABSTRACT

A non-compliant medical balloon, where the non-compliant medical balloon may be changed from a deflated state to an inflated state by increasing pressure within the balloon, is made with a first fiber layer, a second fiber layer over said first fiber layer such that the fibers of the first fiber layer and the fibers of the second fiber layer form an angle and a binding layer coating the first fiber layer and said second fiber layer. The longitudinal extension of the non-compliant medical balloon remains unchanged when the balloon changes from a deflated state to an inflated state

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. patent applicationSer. No. 09/523,817 filed Mar. 13, 2000, which is a continuation-in-partof U.S. patent application Ser. No. 08,873,413, filed Jun. 12, 1997,which claims benefit of U.S. provisional application Ser. No.60/019,931, filed Jun. 14, 1996.

FIELD OF THE INVENTION

[0002] This invention relates to the field of balloons that are usefulin angioplasty and other medical uses.

BACKGROUND OF THE INVENTION

[0003] Catheters having inflatable balloon attachments have been usedfor reaching small areas of the body for medical treatments, such as incoronary angioplasty and the like. Balloons are exposed to large amountsof pressure. Additionally, the profile of balloons must be small inorder to be introduced into blood vessels and other small areas of thebody. Therefore, materials with high strength relative to film thicknessare chosen. An example of these materials is PET (polyethyleneterephthalate), which is useful for providing a non-compliant,high-pressure device. Unfortunately, PET and other materials with highstrength-to-film thickness ratios tend to be scratch- andpuncture-sensitive. Polymers that tend to be less sensitive, such aspolyethylene, nylon, and urethane are compliant and, at the same filmthickness as the non-compliant PET, do not provide the strength requiredto withstand the pressure used for transit in a blood vessel andexpansion to open an occluded vessel. Non-compliance, or the ability notto expand beyond a predetermined size on pressure and to maintainsubstantially a profile, is a desired characteristic for balloons so asnot to rupture or dissect the vessel as the balloon expands. Furtherdifficulties often arise in guiding a balloon catheter into a desiredlocation in a patient due to the friction between the apparatus and thevessel through which the apparatus passes. The result of this frictionis failure of the balloon due to abrasion and puncture during handlingand use and also from over-inflation.

SUMMARY OF THE INVENTION

[0004] The present invention is directed to a non-compliant medicalballoon suitable for angioplasty and other medical procedures and whichintegrally includes very thin inelastic fibers having high tensilestrength, and methods for manufacturing the balloon. The fiberreinforced balloons of the present invention meet the requirements ofmedical balloons by providing superior burst strength; superiorabrasion-, cut- and puncture-resistance; and superior structuralintegrity.

[0005] More particularly, the invention is directed to afiber-reinforced medical balloon having a long axis, wherein the ballooncomprises an inner polymeric wall capable of sustaining pressure wheninflated or expanded and a fiber/polymeric matrix outer wall surroundingand reinforcing the inner polymeric wall. The fiber/polymeric matrixouter wall is formed from at least two layers of fibers and a polymerlayer. The fibers of the first fiber layer are substantially equal inlength to the length of the long axis of the balloon and run along thelength of the long axis. But “substantially equal in length” is meantthat the fiber is at least 75% as long as the length of the long axis ofthe balloon, and preferably is at least 90% as long. The fiber of thesecond fiber layer runs radially around the circumference of the longaxis of the balloon substantially over the entire length of the longaxis. By “substantially over the entire length” is meant that the fiberruns along at least the center 75% of the length of the long axis of theballoon, and preferably runs along at least 90% of the length. The fiberof the second fiber layer is substantially perpendicular to the fibersof the first fiber layer. By “substantially perpendicular to” is meantthat the fiber of the second fiber layer can be up to about 10 degreesfrom the perpendicular.

[0006] The invention is further directed to processes for manufacturinga non-compliant medical balloon. In one embodiment, a thin layer of apolymeric solution is applied onto a mandrel, the mandrel having theshape of a medical balloon and being removable from the finishedproduct. High-strength inelastic fibers are applied to the thin layer ofpolymer with a first fiber layer having fibers running substantiallyalong the length of he long axis of the balloon and a second fiber layerhaving fiber running radially around the circumference of the long axissubstantially over the entire length of the long axis. The fibers arethen coated with a thin layer of a polymeric solution to form afiber/polymeric matrix. The polymers are cured and the mandrel isremoved to give the fiber-reinforced medical balloon.

[0007] In another embodiment of the invention, a polymer balloon isinflated and is maintained in its inflated state, keeping the shape ofthe balloon. High-strength inelastic fibers are applied to the surfaceof the balloon, with a first fiber layer having fibers runningsubstantially along the length of the long axis of the balloon and asecond fiber layer having fiber running radially around thecircumference of the long axis substantially over the entire length ofthe long axis. The fibers are then coated with a thin layer of apolymeric solution to form a fiber/polymeric matrix. The fiber/polymericmatrix is cured to give the fiber-reinforced medical balloon, which canthen be deflated for convenience, until use.

[0008] In a presently preferred embodiment, a thin coating of anadhesive is applied to the inflated polymer balloon or to thepolymer-coated mandrel prior to applying the inelastic fibers.

DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 illustrates an inflated standard medical balloon, which isused in this invention as the base of the final compositefiber-reinforced balloon.

[0010]FIG. 2 illustrates an inflated standard medical balloon, which isused in this invention as the base of the final compositefiber-reinforced balloon.

[0011]FIG. 3 illustrates the positioning of the second layer of fiberover the first fiber layer. The fiber is wound radially around the longaxis substantially over the entire length of the long axis of theballoon, each wrap being substantially equally spaced from the others.The fiber runs substantially perpendicular to the fibers of the firstfiber layer.

[0012]FIG. 4 illustrates the positioning of the third layer of fiberover the second fiber layer, in accordance with another embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[0013] Referring now to the drawings, wherein like reference numbers areused to designate like elements throughout the various views, severalembodiments of the present invention are further described. The figuresare not necessarily drawn to scale, and in some instances the drawingshave been exaggerated or simplified for illustrative purposes only. Oneof ordinary skill in the art will appreciate the many possibleapplications and variations of the present invention based on thefollowing examples of possible embodiments of the present invention.

[0014] A medical balloon in accordance with the present invention in oneembodiment begins with an inflated polymeric balloon 2, as shown in FIG.1, to which there is applied by hand or mechanically, inelastic fiber orfilament 4, as shown in FIG. 2. This is sometimes referred to as the“primary wind.” To assist in placement and retention of the fibers,there can be applied an adhesive to either the inflated balloon surfaceor to the fiber. The purpose of this first application of fiber is toprevent longitudinal extension (growth) of the completed balloon.

[0015] An alternate method of applying the longitudinal fibers involvesfirst creating a fabric of longitudinal fibers by pulling taut multipleparallel fibers on a flat plate and coating with a polymeric solution tocreate a fabric. The fabric is then cut into a pattern such that it canbe wrapped around the base balloon or mandrel.

[0016] Next, a second application of inelastic fiber 6 is applied to thecircumference of the balloon, as shown in FIG. 3. This is sometimesreferred to as the “hoop wind.” The purpose of the hoop wind is toprevent or minimize distension of the completed balloon diameter duringhigh inflation pressures.

[0017] After the hoop wind is completed, the exterior of the fiber-woundinflated balloon is coated with a polymeric solution and cured to form acomposite, con-complain fiber-reinforced medical balloon. The outerpolymeric coating of the fiber/polymeric matrix secures and bonds thefibers to the underlying inflated balloon so that movement of the fibersis restricted during deflation of the composite balloon and subsequentinflation and deflation during use of the balloon. The polymericsolution can be applied several times, if desired. The polymericsolution can use the same polymer as or a polymer different from thepolymer of the inflated polymeric balloon 2. The polymers should becompatible so that separation of the composite balloon is prevented orminimized.

[0018] In a second method of making a medical balloon of the presentinvention, a removable mandrel having the shape that is identical to theshape of the inside of the desired balloon is used. A shape such asshown in FIG. 1 is suitable. The mandrel can be made of collapsiblemetal or polymeric bladder, foams, waxes, low-melting metal alloys, andthe like. The mandrel is first coated with a layer of a polymer, whichis then cured. This forms the inner polymeric wall of the balloon. Next,repeating the steps as described above, the primary wind and the hoopwind are placed over the inner polymer wall, followed by a coating witha polymeric solution and curing thereof to form a fiber/polymeric matrixouter wall. Finally, the mandrel is removed, by methods known in the artsuch as by mechanical action, by solvent, or by temperature change, togive the composite medical balloon of the invention.

[0019] In view of the high strength of the balloons of the presentinvention, it is possible to make balloons having a wall thickness lessthan conventional or prior art balloons without sacrifice of burststrength, abrasion resistance, or puncture resistance. The balloon wallthickness can be less than the thickness given in the exampleshereinbelow.

[0020] In addition, the fiber-reinforced balloons of the presentinvention are non-compliant. That is, they are characterized by minimalaxial stretch and minimal radial distention and by the ability not toexpand beyond a predetermined size on pressure and to maintainsubstantially a profile.

[0021] Polymers and copolymers that can be used for the base balloonand/or the covering layer of the fiber/polymeric matrix include theconventional polymers and copolymers used in medical balloonconstruction, such as, but not limited to, polyethylene, polyethyleneterephthalate (PET), polycaprolactam, polyesters, polyethers,polyamides, polyurethanes, polyimides, ABS copolymers,polyester/polyether block copolymers, ionomer resins, liquid crystalpolymers, and rigid rod polymers.

[0022] The high-strength fibers are chosen to be inelastic. By“inelastic,” as used herein and in the appended claims, is meant thatthe fibers have very minimal elasticity or stretch. Zero elasticity orstretch is probably unobtainable taking into account the sensitivity ofmodem precision test and measurement instruments, affordable costs andother factors. Therefore, the term “inelastic” should be understood tomean fibers that are generally classified as inelastic but which,nevertheless, may have a detectable, but minimal elasticity or stretch.High strength inelastic fibers useful in the present invention includebut are not limited to, Kevlar, Vectran, Spectra, Dacron, Dyneema,Terlon (PBT), Zylon (PBO), Polyimide (PIM), ultra high molecular weightpolyethylene, and the like. In a presently preferred embodiment, thefibers are ribbon-like; that is, they have a flattened to a rectangularshape. The fibers of the first fiber layer may be the same as ordifferent from the fiber of the second fiber layer.

[0023] The most advantageous density of the fiber wind is determinablethrough routine experimentation by one of ordinary skill in the artgiven the examples and guidelines herein. With respect to thelongitudinally-placed fibers (along the long axis of the balloon) of thefirst fiber layer, generally about 15 to 30 fibers having a fiberthickness of about 0.0005 to 0.001 inch and placed equidistant from oneanother will provide adequate strength for a standard-sized medicalballoon. With respect to the fiber of the hoop wind, or second fiberlayer, fiber having a thickness of about 0.0005 to 0.001 inch and a winddensity within the range of about 50 to 80 wraps per inch is generallyadequate. The fiber of the second fiber layer is preferably continuousand is, for a standard-sized medical balloon, about 75-100 inches long.

[0024] The longitudinally placed fibers should be generally parallel toor substantially parallel to the long axis of the balloon for maximumlongitudinal stability (non-stretch) of the balloon. The fibers of thehoop wind should be perpendicular to or substantially perpendicular tothe fibers placed longitudinally for maximum radial stability(non-stretch) of the balloon. This distributes the force on the balloonsurface equally and creates “pixels” of equal shape and size. In thecase where the fibers of the hoop wind are at a small acute angle (e.g.about 10 degrees or more) to the longitudinal fibers, two hoop winds (inopposite directions) can be used for minimizing radial distension. FIG.4 depicts a balloon having a second hoop wind 12.

EXAMPLES

[0025] The following examples are provided to illustrate the practice ofthe present invention, and are intended neither to define nor to limitthe scope of the invention in any manner.

Example 1

[0026] An angioplasty balloon, as shown in FIG. 1, having a wallthickness of 0.0008 inch is inflated to about 100 psi, and the two openends of the balloon are closed off. The inflation pressure maintains theshape (geometry) of the balloon in an inflated profile during theconstruction of the composite balloon. The balloon is a blow-moldedballoon of highly oriented polyethylene terephthalate (PET). To theinflated balloon is applied a very thin coat of 3M-75 adhesive to holdthe fibers sufficiently to prevent them from slipping out of positionafter placement on the balloon.

[0027] Kevlar® fibers are placed, by hand, along the length of theballoon as shown in FIG. 2 to provide the primary wind. Each of thefibers is substantially equal in length to the length of the long axisof the balloon. Twenty-four fibers are used, substantially equallyspaced from each other. The fiber used for the primary wind has athickness of 0.0006 inch.

[0028] Next, a hoop wind of Kevlar® fiber is applied radially around thecircumference of and over substantially the entire length of the longaxis of the balloon, as shown in FIG. 3. The fiber has a thickness of0.0006 inch and is applied at a wind density of 60 wraps per inch.

[0029] The fiber-wound based PET balloon is then coated with a 10%solution of Texin® 5265 polyurethane in dimethylacetamide (DMA) andallowed to cure at room temperature. Five additional coating of thepolurethane solution are applied in about 6-hour increments, after whichthe pressure in the balloon is released. The resulting compositefiber-reinforced balloon is non-compliant and exhibits superior burststrength and abrasion and puncture resistance.

[0030] 3M-75 is a tacky adhesive available from the 3M Company,Minneapolis, Minn. Kevlar® is a high strength, inelastic fiber availablefrom the DuPont Company, Wilmington Del. Texin® 5265 is a polyurethanepolymer available from Miles, Inc., Pittsburgh, Pa.

Example 2

[0031] The procedure of Example 1 was repeated with the exception thatVectran® fiber, having a thickness of 0.0005 inch is used in place ofthe Kevlar® fiber. The resulting composite balloon is axially andradially non-compliant at very high working pressures. The balloon hasvery high tensile strength and abrasion and puncture resistance.

[0032] Vectran® is a high strength fiber available fromHoechst-Celanese, Charlotte, N.C.

[0033] Example 3

[0034] A mandrel in the shape of a balloon as shown in FIG. 1 is made ofa water-soluble wax. The wax mandrel is coated with a very thin layer(0.0002 inch) of Texin® 5265 polyurethane. After curing, adhesive andVectran® fibers are applied, following the procedure of Example 1. Next,several coats of Texin® 5265 polyurethane as applied in Example 1. Thewax is then exhausted by dissolving in hot water to give anon-compliant, very high strength, abrasion-resistant, compositefiber-reinforce balloon.

Example 4

[0035] The procedure of Example 3 is repeated using high strengthSpectra® fiber in place of Vectran® fiber. Spectra® fiber is availablefrom Allied Signal, Inc., Morristown, N.J.

Example 5

[0036] The procedure of Example 1 is repeated using Ultra High MolecularWeight Polyethylene (Spectra 2000) fiber, which has been flattened on aroll mill. To the flattened fiber is applied a thin coat of a solutionof 1-MP Tecoflex® adhesive in a 60-40 solution of methylene chloride andmethylethylketone. The fiber is applied to the balloon as in Example 1using 30 longitudinal fibers, each substantially equal in length to thelength of the long axis of the balloon, and a hoop wind of 54 wraps perinch. The fibers are then coated with the Tecoflex® solution.

[0037] Tecoflex® is supplied by Thermedics Inc., Woburn, Mass.

Example 6

[0038] A balloon-shaped solid mandrel made of a low melting temperaturemetal alloy is coated with a thin layer of Texin® 5265/DMA solution(10%). Vectran® fibers are applied as in Example 1, followed by coatingwith Texin®/DMA. The metal mandrel is melted out using hot water. A veryhigh strength, abrasion-resistant, composite balloon is obtained, whichis non-compliant.

Example 7

[0039] Following the procedures of Example 6, a mandrel is coated with avery thin layer of PIM polyimide (2,2-dimethylbenzidine) in solution incyclopentanone. Polyimide fibers are applied, and the composite balloonis then completed with additional applications of the PIM solution. Themandrel is removed to give a high strength, puncture-resistant balloonhaving an extremely cohesive fiber/matrix composite wall that isresistant to delamination.

Example 8

[0040] A balloon is constructed as in Example 7, except that thelongitudinal fibers are replaced by a longitudinally oriented thin filmmade of polyimide LARC-IA film (available from IMITEC, Schenectady,N.Y.). The film is cut into a mandrel-shaped pattern and applied to themandrel, over which the polyimide hoop fibers and the PIM solution areapplied.

[0041] Although the illustrative embodiment has been described indetail, it should be understood that various changes, substitutions andalterations can be made therein without departing from the spirit andscope of the invention as defined by the appended claims.

What is claimed is:
 1. A non-compliant medical balloon, where thenon-compliant medical balloon may be changed from a deflated state to aninflated state by increasing pressure within the balloon, comprising: afirst fiber layer; a second fiber layer over said first fiber layer suchthat the fibers of the first fiber layer and the fibers of the secondfiber layer form an angle; a binding layer coating the first fiber layerand said second fiber layer; wherein the longitudinal extension of thenon-compliant medical balloon remains substantially unchanged when theballoon changes from a deflated state to an inflated state.
 2. Thenon-compliant medical balloon of claim 1, wherein said first fiber layercomprises inelastic fibers.
 3. The non-compliant medical balloon ofclaim 1, wherein said first fiber layer comprises a plurality ofparallel first fibers.
 4. The non-compliant medical balloon of claim 1,further comprising an adhesive layer adhering to said first fiber layer.5. The non-compliant medical balloon of claim 1, wherein said secondfiber layer comprises a plurality of parallel second fibers.
 6. Thenon-compliant medical balloon of claim 1, wherein said angle issubstantially a right angle.
 7. The non-compliant medical balloon ofclaim 1, wherein said angle does not change when the balloon changesfrom a deflated state to an inflated state.
 8. The non-compliant medicalballoon of claim 3, wherein said plurality of parallel first fibers aresubstantially parallel to the longitudinal axis of the balloon.
 9. Thenon-compliant medical balloon of claim 5, wherein said plurality ofparallel second fibers are substantially transverse to the longitudinalaxis of the balloon.
 10. The non-compliant medical balloon of claim 1,wherein said binding layer is a polymeric coating.
 11. The non-compliantmedical balloon of claim 10, wherein said polymeric coating is formed ofa polymer.
 12. The non-compliant medical balloon of claim 10, whereinsaid polymeric coating is formed of a copolymer.
 13. The non-compliantmedical balloon of claim 3, wherein said parallel first fibers each havea thickness of about 0.0005 inch.
 14. The non-compliant medical balloonof claim 5, wherein said parallel second fibers each have a thickness ofabout 0.0005 inch.
 15. The non-compliant medical balloon of claim 5,wherein said parallel second fibers have a wind density of approximately50 wraps per inch.
 16. The non-compliant medical balloon of claim 1,wherein said angle is about ten degrees.
 17. The non-compliant medicalballoon of claim 1, further comprising a third fiber layer on saidsecond fiber layer.